Often a cancer patient will come into our office for secondary or supportive care to the primary cancer treatment they are receiving. One of the first things their loved ones will usually say in our first meeting is, “I wish they told us about these side effects so we could be prepared.” Among the side effects, cognitive function and challenges of mental health.
In December 2018, researchers writing in the journal BioMed Central cancer, (1) echoed these concerns “Cognitive deficits are common complications of breast cancer survivors treated with chemotherapy. The most frequently observed disorders involve executive function and memory impairment. With improvements in tumor intervention and the consequent increase in the number of cancer survivors, the quality of life of patients has become an important issue.”
We are going to return to this new research, but first let’s explore the well known effect of chemotherapy, “chemo brain.” This is a “brain fog sensation,” a loss of memory and cognitive function during and after chemotherapy or radiotherapy treatments.
Most research reports that these are temporary conditions. Symptoms should be treated with various methods including memory and brain exercises when needed. Also included in the treatment methods are certain Alzheimer medications and those medications for attention-deficit disorder. However, new research is suggesting doctors look at how to manage post chemo and radiation therapy inflammation for possible answers.
Initially it was thought that the side effects of chemotherapy were solely responsible for “chemo brain.” This limitation to chemotherapy causing effects was challenged by a research team from the Moffitt Cancer Center and Research Institute working with associates from the University of South Florida and the University of Kentucky.
In a study they published in the medical journal Cancer, (2) changes in cognitive functioning over time were compared in:
- (1) breast cancer survivors treated with chemotherapy plus radiotherapy,
- (2) breast cancer survivors treated with radiotherapy only, and
- (3) women with no history of cancer.
The researchers noted cognitive problems for up to three years post chemo. What they also found in test subjects was that not only did chemotherapy lead to what is commonly referred to as “Chemo Brain,” but radiotherapy did as well.
Referring back to the December 2018 study we referenced at the beginning of this article, the researchers of this study suggested that the impact of chemotherapy on brain function in breast cancer survivors who were given chemotherapy: “provide further evidence that adjuvant chemotherapy (chemotherapy provided after initial treatment to address secondary cancers) is associated with demyelination of white matter (damage to the protective myelin sheath covering that surrounds nerve fibers in your brain.)”In addition, adjuvant chemotherapy affected the integrity of white matter (the nerves and myelin sheath of the “deep brain,” resulted in poor cognitive performance.”
The researchers concluded that the brain network integration of breast cancer survivors became worse. That their study demonstrated alterations in the structural brain networks of breast cancer survivors.
But what impact does “alterations in the structural brain networks of breast cancer survivors,” have beyond cognitive function?
Another December 2018 study in the Journal of the National Cancer Institute (3) noted: “There is compelling evidence of an increased risk of anxiety, depression and suicide, and neurocognitive and sexual dysfunctions in breast cancer survivors compared with women with no prior cancer.”
Inflammation and its role in the mental health of breast cancer survivors
In June 2018, researchers publishing in the journal Frontiers in immunology, (4) opened their study with this paragraph:
“Behavioral comorbidities (depression, anxiety, fatigue, cognitive disturbances, and neuropathic pain) are prevalent in cancer patients and survivors. These mental and neurological health issues reduce quality-of-life, which is a significant societal concern given the increasing rates of long-term survival after various cancers. Hypothesized causes of behavioral comorbidities with cancer include tumor biology, stress associated with the cancer experience, and cancer treatments. A relatively recent leading mechanism by which these causes contribute to changes in neurobiology that underlie behavior is inflammation. Indeed, both basic and clinical research indicates that peripheral inflammation leads to central inflammation and behavioral changes in other illness contexts.“
Inflammation is used to treat cancer tumors:
In the cancer journal Oncotarget, (5) researchers noted cancer patients often report behavioral and cognitive changes following cancer treatment. that treatments combining radiotherapy and immunotherapy demonstrated remarkable efficacy with respect to tumor outcomes by enhancing the proinflammatory environment in the tumor. (Immunotherapy enhances the immune response to invading cells like cancer, flu or cold, by increasing inflammation).
However, a pro-inflammatory environment in the brain causes and induces cognitive impairments and may affect brain function in cancer patients receiving these treatments.
The research team from Oregon Health and Science University behind this research concluded that, “Although combined treatment achieved tumor growth control, it affected the brain and induced changes in measures of anxiety, cognitive impairments, and neuroinflammation.”
Inflammation opens a door for neurotoxicity and cognitive dysfunction
The focus here is on cytokines – a small protein that communicates with immune cells to get them to the site of injury, infection, and inflammation. The thinking is that cytokines are somehow opening a doorway in “blood-brain barrier” the blood filtering mechanism that carries blood to the brain while blocking many harmful substances. It is through that it is through this doorway that “unfiltered” chemicals are getting through into the brain.
In research from the International Journal of Cancer, (6) doctors looked at the neurotoxicity side effect of chemotherapy treatment. Here is what they wrote:
- Clinical studies suggest that the most frequent neurotoxic adverse events affect memory and learning, attention, concentration, processing speeds and executive function.
- Emerging pre-clinical research points toward direct cellular toxicity and induction of neuroinflammation as key drivers of neurotoxicity and subsequent cognitive impairment. (The research suggests that the chemicals used in chemotherapy are somehow bypassing the blood – brain barrier., as we mentioned above.)
- Emerging data now show detectable levels of some chemotherapeutic agents within the central nervous system, indicating potential disruption of blood brain barrier integrity.
Blood brain barrier disruption is a key aspect of many neurocognitive disorders, particularly those characterized by a pro-inflammatory state.
Research from doctors in the Czech Republic (7) reported that cognitive impairment (impairment of memory, attention, or concentration) is documented in 17-75% of patients with various malignancies treated with chemotherapeutic agents that worsen quality of life.
- Changes occur mainly in the ability to learn and remember, in the speed of reactions, and in attention and executive functions.
- Although Chemo-related cognitive impairment’s complexities are not yet fully understood, the involvement of neurotoxicity, such as that induced by treatment, anemia, higher levels of oxidative stress and inflammatory responses, genetic factors, and reduced brain connectivity should be discussed.
Omega 3 and sugar reduction can help
The link between inflammation post chemotherapy and radiotherapy has been shown. Is there anything that can help? Research suggests dietary changes may offer some benefit.
In the medical journal Breast cancer research and treatment, (8) a paper entitled, “Clearing the fog: a review of the effects of dietary omega-3 fatty acids and added sugars on chemotherapy-induced cognitive deficits,”doctors from Ohio State University suggested that:
- Dietary approaches that modify inflammation and neurogenesis (growth of nervous system tissue) are promising strategies for reducing chemotherapy-induced cognitive deficits in breast cancer survivors.
- Omega-3 fatty acids administered concurrently with doxorubicin chemotherapy have been shown to prevent depressive-like behaviors and reduce neuroinflammation, oxidative stress, and neural apoptosis (nerve cell death) in animal studies.
- In contrast, diets high in added sugars may interact with the Omega-3s to diminish their anti-inflammatory activity. The sugars may also act independently to increase neuroinflammation and promote cognitive deficits.
- A diet rich in long-chain, marine-derived omega-3 fatty acids (fish oils) and low in added sugars may be an ideal pattern for preventing or alleviating neuroinflammation and oxidative stress, thereby protecting neurons from the toxic effects of chemotherapy.
- Research testing this hypothesis could lead to the identification of modifiable dietary choices to reduce the long-term impact of chemotherapy on the cognitive functions that are important to quality of life in breast cancer survivors.
1 Li TY, Chen VC, Yeh DC, Huang SL, Chen CN, Chai JW, Chen CC, Weng JC. Investigation of chemotherapy-induced brain structural alterations in breast cancer patients with generalized q-sampling MRI and graph theoretical analysis. BMC cancer. 2018 Dec;18(1):1211.
2 Cognitive functioning after cancer treatment: A three-year longitudinal comparison of breast cancer survivors treated with chemotherapy or radiation and non-cancer controls.” Phillips KM, Jim HS, Small BJ, et al. CANCER; Published Online: December 12, 2011.
3 Carreira H, Williams R, Müller M, Harewood R, Stanway S, Bhaskaran K. Associations Between Breast Cancer Survivorship and Adverse Mental Health Outcomes: A Systematic Review. JNCI: Journal of the National Cancer Institute. 2018 Nov 7;110(12):1311-27.
4 Dos Santos JC, Pyter LM. Neuroimmunology of behavioral comorbidities associated with cancer and cancer treatments. Frontiers in immunology. 2018;9:1195.
5 McGinnis GJ, Friedman D, Young KH, et al. Neuroinflammatory and cognitive consequences of combined radiation and immunotherapy in a novel preclinical model. Oncotarget. 2017;8(6):9155-9173. doi:10.18632/oncotarget.13551.
6 Wardill HR, Mander KA, Van Sebille YZ, Gibson RJ, Logan RM, Bowen JM, Sonis ST. Cytokine-mediated blood brain barrier disruption as a conduit for cancer/chemotherapy-associated neurotoxicity and cognitive dysfunction. Int JCancer. 2016
7. Fayette D, Gahérová Ľ, Móciková H, Marková J, Kozák T, Horáček J. Chemotherapy-related Cognitive Impairment in Patients with Hodgkin Lymphoma-Pathophysiology and Risk Factors. Klinicka onkologie: casopis Ceske a Slovenske onkologicke spolecnosti. 2017;30(2):93-9.
8. Orchard TS, Gaudier-Diaz MM, Weinhold KR, DeVries AC. Clearing the fog: a review of the effects of dietary omega-3 fatty acids and added sugars on chemotherapy-induced cognitive deficits. Breast cancer research and treatment. 2017;161(3):391-398. doi:10.1007/s10549-016-4073-8.